From 9387d575d0319e5fd1b4382b819ed6087e4d5d06 Mon Sep 17 00:00:00 2001
From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Sun, 18 Mar 2012 11:07:47 +0000
Subject: [PATCH] --- yaml --- r: 291595 b: refs/heads/master c:
 c8628155ece363487b57d33441ea0359018c0fa7 h: refs/heads/master i:   291593:
 f15ca6ca24d169947b86ea0a89387e3ab5c131c6   291591:
 da7098b3ef9fc9d3272b81d27ad38e999c294ebd v: v3

---
 [refs]                     |  2 +-
 trunk/include/linux/snmp.h |  1 +
 trunk/net/ipv4/proc.c      |  1 +
 trunk/net/ipv4/tcp_input.c | 19 ++++++++++++++++++-
 4 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/[refs] b/[refs]
index ed3db6cbca76..9d271f7985fe 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: e86b291962cbf477e35d983d312428cf737bc0f8
+refs/heads/master: c8628155ece363487b57d33441ea0359018c0fa7
diff --git a/trunk/include/linux/snmp.h b/trunk/include/linux/snmp.h
index 8ee8af4e6da9..2e68f5ba0389 100644
--- a/trunk/include/linux/snmp.h
+++ b/trunk/include/linux/snmp.h
@@ -233,6 +233,7 @@ enum
 	LINUX_MIB_TCPREQQFULLDOCOOKIES,		/* TCPReqQFullDoCookies */
 	LINUX_MIB_TCPREQQFULLDROP,		/* TCPReqQFullDrop */
 	LINUX_MIB_TCPRETRANSFAIL,		/* TCPRetransFail */
+	LINUX_MIB_TCPRCVCOALESCE,			/* TCPRcvCoalesce */
 	__LINUX_MIB_MAX
 };
 
diff --git a/trunk/net/ipv4/proc.c b/trunk/net/ipv4/proc.c
index 02d61079f08b..8af0d44e4e22 100644
--- a/trunk/net/ipv4/proc.c
+++ b/trunk/net/ipv4/proc.c
@@ -257,6 +257,7 @@ static const struct snmp_mib snmp4_net_list[] = {
 	SNMP_MIB_ITEM("TCPReqQFullDoCookies", LINUX_MIB_TCPREQQFULLDOCOOKIES),
 	SNMP_MIB_ITEM("TCPReqQFullDrop", LINUX_MIB_TCPREQQFULLDROP),
 	SNMP_MIB_ITEM("TCPRetransFail", LINUX_MIB_TCPRETRANSFAIL),
+	SNMP_MIB_ITEM("TCPRcvCoalesce", LINUX_MIB_TCPRCVCOALESCE),
 	SNMP_MIB_SENTINEL
 };
 
diff --git a/trunk/net/ipv4/tcp_input.c b/trunk/net/ipv4/tcp_input.c
index fa7de12c4a52..e886e2f7fa8d 100644
--- a/trunk/net/ipv4/tcp_input.c
+++ b/trunk/net/ipv4/tcp_input.c
@@ -4484,7 +4484,24 @@ static void tcp_data_queue_ofo(struct sock *sk, struct sk_buff *skb)
 	end_seq = TCP_SKB_CB(skb)->end_seq;
 
 	if (seq == TCP_SKB_CB(skb1)->end_seq) {
-		__skb_queue_after(&tp->out_of_order_queue, skb1, skb);
+		/* Packets in ofo can stay in queue a long time.
+		 * Better try to coalesce them right now
+		 * to avoid future tcp_collapse_ofo_queue(),
+		 * probably the most expensive function in tcp stack.
+		 */
+		if (skb->len <= skb_tailroom(skb1) && !tcp_hdr(skb)->fin) {
+			NET_INC_STATS_BH(sock_net(sk),
+					 LINUX_MIB_TCPRCVCOALESCE);
+			BUG_ON(skb_copy_bits(skb, 0,
+					     skb_put(skb1, skb->len),
+					     skb->len));
+			TCP_SKB_CB(skb1)->end_seq = end_seq;
+			TCP_SKB_CB(skb1)->ack_seq = TCP_SKB_CB(skb)->ack_seq;
+			__kfree_skb(skb);
+			skb = NULL;
+		} else {
+			__skb_queue_after(&tp->out_of_order_queue, skb1, skb);
+		}
 
 		if (!tp->rx_opt.num_sacks ||
 		    tp->selective_acks[0].end_seq != seq)